Vibration recording instrument



Dec. 8, 1936. v. E. CARBONARA VIBRATION RECORDING INSTRUMENT 5 Sheets-Sheet 1 Filed Aug. 4, 1952 menu-Hanna A TTORNEY Dec. 8, 1936. v. E. CARBQNARA VIBRATION RECORDING INSTRUMENT Filed Aug. 4, 1932 3 SheetsSheet 2 Dec. 8, 1936. v. E. CARBONARA VIBRATION RECORDING INSTRUMENT Filed Aug. 4, 1932 s She ets-Sheet s INVENTOR. wcro/e E. CARBONARA.

, MMZMM ATTORNEY Patented Dec. 8, 193

Victor E. Carbonara, Rockville Centre,

- signor to Bendix Aviation Corporation,

N. Y., as-

South Bend, Ind., a corporation'of Delaware Application August 4, 1932, Serial No. 627,483

4 Claims.

This invention relates to recording instruments, and more particularly to means for recording vibrations.

One of the objects of the present invention is to provide novel means for recording the fundamental characteristics of vibrations, that is, the amplitude, form and/or frequency of said vibra ons.

Another object of this invention is to provide a after the vibration characteristics of a member upon which it is adapted to be mounted.

A further object is to provide a novel vibration recording instrument of the photographic type which is adapted for use in determining the nature of the vibrations of a movable .structure such as, for example, the instrument board of an airplane.

A still further object is to provide novel means for obtaining a visual record of the characteristics of the component of the vibrations imparted to a member along one or a plurality of axes irrespective of their angular relation to one another.

Another object is to provide novel means in a vibration recording instrument, or vibrograph, for producing a substantially undistorted, uniform record of the amplitudes and frequencies of the components of vibrations impartedto the instrument along a plurality of axes.

The above and further objects and novel features of the present invention will more fully appear from the following detailed description when ing drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only andare not designed as a definition of the limits of the invention, reference being primarily had for this purpose to the appended claims.

wherein life reference charac- In the drawings ters refer to like parts throughout the several views:-

Fig. 1 is a side elevation, partly in section and with parts broken away, of an instrument embody the present invention;

Fig.'2 is a transverse view of the same taken taken in connection with the accompanymember and vibrating on line 2-2 of Fig. l with theprisms in the rear of the casing removed; Fig. 3 is a schematic view of one form ofthe' power mechanism and the optical system which may be employed in. carrying out thepresent 5 invention;

Fig. 4 is a cross-sectional view, with parts broken away, taken on line 4-4 of Fig. 1;

Fig. 5 is a front end view;

Fig. 6 is a top plan view, with parts broken away, shown in Fig. 1; g

Fig. 7 is a detail view, partly in'section, illustrating a portion of one form of steadying means for the reference member employed in out the invention;

Fig. 8 is a detail view showing a portion of the optical system employed; and

Fig. 9 is an enlarged perspective illustrating a light directing member Only one embodiment or vibration recording instrument, comprehended by the present invention, has been illustrated in 4 of the instrument the accompanying drawings in which the instrupartly in section and 10 carrying 15 which may be employed. 20 of the novel vibrograph ment is shown as comprising a cylindrical hous- 25 mg 5, to the rear of by means of a pin and slot connection a metal cup 6, the members 5, 6 constituting the instrument case. A disc I secured toan internal flange in housing 5 constitutes a partition which divides the instrument case into rear and front compartments, the latter being closed by a disc 8 secured in any suitable manner to the front end of housing 5. Said .housing is provided with which is detachably secured J a plurality of flanged openings 9 (Fig. 4) about 35 its periphery, the purpose of which will be hereinafter explained. Preferably, four such openings are provided and, as shown, are spaced at substantially 5 degrees on either side of the vertical center line of housing 5. Each of said openings may be pro 'ded with a cup-shaped cover In. The case is adapted to be mounted on a vibrating member and, accordingly. when so mounted the vibrations of the member are imparted to the same.

In order to obtain a record of the amplitude and form of the .vibrations to which the case is thus subjected, it is necessary to refer the vibratory motion to a member whose motion is constant and the character of which is lmown.

The relative movement between the reference member may then be determined and from this the true characteristics of the vibratory motion maybe calculated.

if a stationary reference ember is provided, I

.together with means for recording the relative motion along these axes between the casin and the reference member. The reference member provided will be referred to as being stationary since it has no appreciable movement in any plane with respect to the casing, that is, the reference member remains stationary while the casing vibrates about it. It is thus possible to obtain faithful records of the components of the vibrational motions of a member resolved along any desired axis, and such records may be compared with-an arbitrary standard for obtaining the desired data.

The stationary reference member employed in carrying out the present invention preferably comprises an inertia member in the form of a cylindrical block or mass l2 suspended by means of a plurality of yielding members such as coil springs I3 in the front portion of housing 5 in a manner such that the longitudinal axis of said mass coincides with the longitudinal axis of. the instrument case 5, 6. Two springs I 3 are attached to each of four eyelets secured to mass l2 at points in which the transverse horizontal and vertical axes of said mass intersect the periphery of the same. The springs are anchored to the instrument case 5, 6 by means of suitable adjusting screws l4 threaded into brackets l 5 which are in turn secured by set screws to the flanged portions of openings 9. Suitable lock nuts I6 may be provided for adjusting screws M, the latter serving as a means for adjusting the tension of springs 13. In order that mass l2 may be independent of the vibrations of the case and therefore remain stationary, experiments have shown that the tension of springs l3 should be such that the natural frequency of the system is substantially one-fifth or less of the lowest frequency which it is desired to record.

That the relative movement between the case and the stationary mass is a true measure of the vibrations imparted to the case will now be clearly apparent. Although the amplitude and frequency ofthe components of the vibrations resolved along any desired axis may be obtained with a reference member of the above character, it is desirable to record only such data as will enable an observer to readily refer the same to the axis concerning which information is desired. In the illustrated form of the invention, therefore, provision has been made for recording the resolved components of the vibrations alon three mutually perpendicular axes, mainly those axes corresponding to the longitudinal, vertical and transverse axes of the instrument.

For the purpose of obtaining these records, the present invention comprehends novel means for first converting the lineal components of. the relative or vibratory motion along the three above named axes into angular motion of refleeting members, each of which representsone of said axes, As shown, such means are constituted by a plate l'l (Figs. 1 and 6) suitably secured to the rear faceof mass l2 and spaced therefrom by means of washers. Plate l1 supports three screws l8, l9 and 20 (Fig. 4), the former being threadedly received by the plate itself and having its axis parallel to the longitudinal axis of the instrument, whereas the latter two are threadedly mounted in brackets 2i and 22 suitably secured to said plate and have their axes parallel to the transverse and vertical axes of the instrument case, respectively. These screws are threaded for the purpose of making calibrational adjustments and may be provided with suitable lock nuts 23. The inner ends of screws l8, l9 and 20 are ground to a plane surface and polished for reasons which will hereinafter appear. Since the above assembly is wholly supported by mass l2, the same will remain stationary with said mass.

Considering first the conversion of the longitudinal components of the vibrations, a vertically disposed rocker shaft 24 is rotatably supported by a pair of bearing plates 25 mounted on U- shaped brackets 26 which are secured in any suitable mannerto disc I. An arm 21 is operatively secured to shaft 24 and extends laterally therefrom in a direction parallel to the transverse axis of the instrument case 5, 6 so that the periphery of an enlarged disc-like portion on the end thereof is in sliding engagement with the polished end surface of screw [8. Any suitable means, such as a spring 28, may be provided for holding arm 21 in engagement 'with said surface. Thus, arm 21 is free to oscillate "angularly in a horizontal plane perpendicular to the end surface of screw l8 because the outer end of. the same is prevented from following the longitudinal vibrations of the instrument due to the fact that said screw is stationary as pointed out above. Shaft 24, on the other hand, vibrates with the instrument in this latter direction and is thereby rocked about its vertical axis through the oscillating action of arm 21 by an amount proportionalto and in accordance with the longitudinal component of the vibrations to which the instrument is subjected.

The component of the vibratory movement of the case resolved along a transverse axis is converted into angular motion of shaft 29 mounted in the same manner as shaft 24 and provided with a horizontal arm 30 (Fig. 6) similar to arm 21, which extends parallel to the longitudinal axis of the instrument and is slidably held against the end surface of screw l9 by means of a suitable spring corresponding to spring 28. Arm 30 is, therefore, free to oscillate angularly in a horizontal plane perpendicular to the end surface of screw l9 and is adapted to rock shaft 29 about a vertical axis in accordance with the transverse component of the vibratory motion of the case.

For converting the vertical component of the vibrations into like angular motion, a vertically oscillating movement in a vertical direction takes place between spindle 3| and plates 25 when the latter vibrate vertically with the instrument casing 5, 6. Said spindle is provided with an inclined or conical portion 33 near its center.

A shaft 34, corresponding to shafts 24 and 29, has a laterally extending arm 35 operatively attached thereto and extending laterally therefrom, said arm having an enlarged cylindrically shaped end portion which is adapted to be resiliently held in sliding engagement with the inclined surface of cone 33. As the outer end of arm 35 moves vertically with shaft 34 and plates 25 in response to the vibrations of the instrument case 5, 6, it is caused to follow the inclined surface of cone 33 and is' thus oscillated angularly in a horizontal plane parallel to the end surface of screw 26, thereby rocking shaft 34 about a vertical axis in proportion to the amplitude of the vertical component of the vibrations of the case.

Shafts'24, 29 and 34 have extensions 'below the lower plate 25, said extensions being of varying lengths with that of shaft 29 the shortest and that of shaft 24 the longest. These extensions are provided at the lower ends of the same with enlarged cylindrical portions, the lower halves of which are cut away on a diameter that intersects the longitudinal axisof the instrument at an angle of substantially 45 degrees, and suitable reflecting members such as mirrors 24a, 29a and 34a are mounted on the fiat surfaces thus formed.

Means are provided within casing 5, 6 for pro jecting a beam of light against each of the angularly movable mirrors 24a, 29a. and 34a, thus making it possible to photographically record the rocking motion of said mirrors, which motion is representative of the components of the vibrations under investigation taken along the longitudinal, transverse and vertical axes of the casing, For this purpose, there is employed a small electric bulb 350 (Fig. 4) that is connected to a suitable source of current such as a batte (not shown). in any convenient manner in the side of housing in line with mirrors 24a, 29a and 34a. Lamp socket 36 is surrounded by an opaque sleeve 31 and threaded into the inner end thereof having an extension tube 38 which carries at its inner end a pair of condenser lenses 39. The latter direct light beams through three small apertures 40 in a cup-shaped member threaded onto the inner end of tube 38. From apertures 40, the light beamsare projected against mirrors 24a, 29a. and 340'. Thus the light beams striking the mirrors all have angular oscillating motions impartedthereto in parallel horizontal planes and are then passed through a convergent lens 4| into the rear compartment of casing 5, 6, and through a rotatably mounted deflector or erecting prism 42, the purpose of which will be hereinafter described.

Means are provided for increasing the optical leverage of the beams so that with an instrument of small size a readily readable record may be obtained of vibrations having small amplitude and high frequency such as, for example, the vibrations imparted to the instrument board of an airplane. Preferably, such means are constituted by a pair of stationary prisms 43 and 44 (Figs. 1, 3 and 8) mounted in the rear of casing 5, 6, in a frame. supported by rods 45. As will be noted in Fig. 4, prisms 43, 44 reflect the light beams through substantially 180 degrees onto a movable mirror 46 to be more fully described hereinafter.

Means are provided for positioning a light order that a permanent visible record may be obtained of the amplitude, form and frequency The lamp is mounted of the vibrations or vibration components to be measured. For this purpose, there are provided a pair of film-carrying spools 41 and 48 mounted in suitable magazines or tubes 49 and 58 (Fig. 2), respectively, the latter in turn being suitably secured as by solder to disc 1. Arcuate guides 5| are provided on either side of the film for guiding the same from one spool to the other. A shaft 52, which projects through the face plate 8 and is provided 'on its outer end with a knob 53, may be employed for rotating spool 41 to wind the film from spool 48 to spool 41 and expose lengths of .the same to the light beams as desired.

Means are provided for indicating the number of film exposures made and, as illustrated,

.such means comprise a shaft 54 journaled in discs 1 and 8, and provided on its inner end with a sprocket 55 that meshes with suitably spaced holes near the edge of the film. Shaft 54 is provided at its other end with a pinion 56 which normally meshes with an indicating dial 51 that is supported by means of a shaft 58 in disc 8 and is visible through a small opening 59 in said disc. Shaft 58 may be provided with a knob 60 (Fig. l) which slidably fitsover'a sleeve 6|, thus making it possible to move dial 51 out of mesh with pinion 56 for setting the same at zero reading' without disturbing the spool 48 when a new roll of film has been inserted. Dial 51 is normally maintained in mesh with pinion 56 by means of a spring '62 interposed between knob 60 and sleeve 6|.

If mirror. 46 and the film are relatively stationary, only a plurality of superimposed exposures are obtained, and it would be impossible to determine from such a record the frequency of the vibrations or the varying amplitudes of the same if such should exist. The present invention, therefore, comprehends the use of a mirror adapted to be intermittently moved relative to the film for predetermined intervals of time. By counting the number of vibration cycles as recorded-on the film during each of said intervals, the frequency is readily determined.

In the form illustrated, the means employed for rotating the mirror are constitutedby a watch mechanism which comprises a pair of main spring housings or drums 63 and 64 '(Fig. 3) in which coil springs (not shown) areadapted to be mounted. Said springs may be normally ound by means of a shaft 65 provided with a knob 65a through a train of gears 66, 61,68 and 63, respectively. The spring in drum 63, as soon as the same is energized, drives the outer toothed portion thereof and rotates shaft 10. The latter is frictionally engaged by and drives a sleeve 1| to which mirror 46 is secured.

P As pointed out above, it is desirable to imwhich is in mesh with a pinion 16. The lower,

end of shaft 16a, on' which said pinion is mounted, is provided with a flipper 11 "which engages a star 18, the rotation of which 'cdntrolled by a conventional escapement wheel and arm 19 and-80, respectively, and a balance wheel 8| such as is used for controlling the ticking actionof a watch. Pressure is placed upon the above assembly by the spring in drum 64 through pinion I6, flipper TI and star 18. When the star has been permitted by escapement wheel 19 to move sufficiently to .release the flipper, the latter will turn onehalf of a revolution when the star will again stop it. Drum 64 and-hence cam 14 are thus permitted to move also, the gear ratio between pinion l6 and drum 64 being such that after the flipper I1 is released, cam 14 moves just enough to shift the end of pawl 13 from a land to a groove or viceversa. When the latter is riding on a land, it exerts a pressure against disc 12 suflicient to overcome the friction between shaft 10 and sleeve II, thereby stopping mirror 46. When the pawl is in a groove of cam 14, sleeve II and mirror 46 are free to rotate with shaft 10.

' If the light beams were allowed to travel at all times towards the rotating mirror 46 in the paths shown in Fig. 3, a distorted record of the two outer beams would be obtained since the photo graphed image would be completely inverted once during each revolution of the mirror. Means are, therefore, provided for counteracting this efiect of the mirror in order that anundistorted record may be obtained and, preferably, such means comprise an erecting prism 42 which is so constructed as to invert an image which passes through the same and which is adjustably mounted by means of set screws 83 in' a ro tatable sleeve 84 (Fig. 1). Since the prism has the same effect upon the beams during a half revolution as does mirror 46 in a full revolution, the former is driven at one-half the speed of the latter through suitably proportioned idler gears 85 and 85a which are interposed between a gear 86 on sleeve II and a gear 86a on sleeve 84.

Means are provided for preventing sudden accelerations of the clockwork or watch mechanism and for maintaining the speed of rotation of mirror 46 substantially constant. Such means are constituted by a train 'of step-up gearing such as gears 81, 88 and 89, the former being in mesh with drum 63 and the latter having a wind vane 90 drivably connected thereto. An inertia mass 9l may be frictionally mounted on shaft 160. for preventing excessively sudden starting and stopping of flipper TI.

It will be noted that the light beams are directed in slightly diverging paths so that by the time the beams reach the photographic film, the divergence will be such that a separate and distinct record of each of the vibration components is obtained. Since these are magnified records, it is necessary to calibrate the instrument to determine the amplification constant before the same is placed in use. Any member which follows a motion, the characteristics of which are known, and to which the instrument can be conveniently attached, may be used as a standard for this purpose.

If desired, means may be provided for holding mass I! in a fixed position during violent maneuvers or when transporting the instrument. The

means herein provided for this purpose (Figs. 1 and 7) consists of a pin 92 which extends through the side of housing and is provided with a conical end portion which fits into a conical depression in said mass, the'latterbeing adapted to be moved by said pin into contact with a pair of felt-lined, ,U-shaped members 93 suitably secured to housing 5 about 120 degrees on either side of pin 92. The latter is held in the desired position by a spring-pressed pawl 94 which engages grooves in said pin.

. angular motion.

In operation, light 35a is first illuminated, a new length of film .is exposed by turning knob 53, and the springs in drums 53 and 64 are energized by turning knob 65a. Mirror 46 is then intermittently rotated for definite intervals of time as explained in detail above. The rays from ror 46 and the film. When mirror 46 is rotating,

a record such as shown in Fig. 3 is obtained.

There is thus provided a novel method for recording vibration characteristics and a novel vibration recording instrument for carrying out said method, said instrument employing novel means for converting the component of the vibrations of .a member along any axis into Novel means are also provided for obtaining an undistorted readily readable record of such component, a record from which the characteristics of thevibrations of said member may be readily ascertained. Moreover, the instrument provided is of such size and weight that the same will not substantially alter the vibrating characteristics of the member, upon which it is mounted and is of such nature that-it is adapted for recording the vibrations of a movable structure such as an airplane for example.

Although only one embodiment of the invention has been illustrated and described, it is to be expressly understood that the same is not limited thereto but that various changes may be made. Reference will, therefore, be had, primarily, to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. In a recording instrument of the type including a casing having a mass resiliently mounted therein for relative movement between it and the casing in at least two mutually perpendicular directions, and also having light-projecting and photographic image-receiving means therein for producing a photographic record of the amplitude and frequency of vibrations in each of said directions, respectively, upon relative movement between said mass and casing, the combination of a support secured to and movable with said casing, a plurality of spindles journaled in said support, one for each corresponding direction in which vibrations are to be recorded, means carried by the mass and engaging said spindles for causing the latter to move angularly according to the respective directions sensitive film, and a timingmechanism for rotating said reflecting members at predetermined times for predetermined intervals. I

. 2. In a recording instrument of the type Gil including a casing having a massresiliently mounted therein for relative movement between it and the casing in at least two mutually perpendicular directions, and also having lightprojecting and photographic image-receiving means therein for producing a photographic record of the amplitude and frequency of vibrations in each of said directions, respectively, upon relative movement between said mass and easing, the combination of a support secured to and movable with said'casing, a plurality of spindles journaled in said support, one for each corresponding direction in which vibrations are to be recorded, means carried by the mass and engaging said spindles for causing said spindles to move angularly according to the respective directions of vibrations and according to the magnitude of said vibrations upon-relative movement between the casing and mass due to said vibrations, a mirror on each. spindle and movable therewith whereby a light beam projected on each of said mirrors is caused to vibrate, a pair of light-reflecting members simultaneously rotatable at, difierent speeds by means of which each of said vibrating light beams from each of said mirrors, respectively, is reflected onto a stationary light sensitive film, and a spring-actuated clock mechanism for rotating said reflecting members at predetermined times for predetermined intervals.

3. In a recording instrument of the type including a casing having a mass resiliently mounted therein for relative movement between it and the casing in at least two mutually perpendicular directions, and also having lightprojecting and photographic image-receiving means therein for producing a photographic record of the amplitude and frequency of vibrations in each of said directions, respectively, upon relative movement between said mass and easing, the combination of a support secured to and movable with said casing, a plurality of spindles journaled in said support, one for each corresponding direction in which vibrations are to be recorded, means carried by the mass and engaging said spindles for causing the latter to move angularly on their respective axes according to the respective directions of vibrations and according to the magnitude, of said vibrations upon relative movement between the casing and mass due to said vibrations, a mirror on each spindle and'movable therewith whereby a light beam projected on each of said mirrors is caused to vibrate, 'a rotatable reflecting member by means of which each of said vibrating light beams from each of said mirrors, respectively, is reflected onto a stationary light-sensitive film, and a timing mechanism for rotating said reflecting member at predetermined times for predetermined intervals.

4. In a recording instrument of the type including a casing having a mass resiliently mounted therein for relative movement between it and the casing in at least two mutually perpendicular directions, and also having light-projecting and photographic image-receiving means therein for producing a photographic record of movable with said casing, 'a plurality of spindles each spindle and movable therewith whereby a light beam projected on each of said mirrors is caused to vibrate, a' rotatable reflecting mem-'- ber by means of which each of said vibrating light beams from each of said mirrors, respectively, is reflected onto a stationary light-sensitive film, and a spring-actuated clock mechanism for rotating said reflecting member at predetermined times for predetermined intervals.

VICTOR E. CARBONARA. 

